Thanks in Advance. I am using keil HID example and win-api to make a usb hid device for sending and receiving data using interrupt transfer. I define the package size as 64 bytes, and of cause if the data sended by the device less than 64 bytes, the host(Overlapped mode) will come up with a timeout error. And I do search in the forum, everybody says I should send a ZLP(zero length package), but I could not find any detail about what ZLP real is, and how to send a ZLP by the device or by the host. So I will appreciate if anybody tell me what can I do. Forgive my fool. Thanks again.
John, thank you very much.I think I have understand what you mining. In fact, I have mix up the Hid and the vendor device. Sorry to border you. Thanks again.